


A Convenient Arrangement

by CornishKid



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Alpha John, Alpha/Beta/Omega Dynamics, Bonding, F/M, Friends to Lovers, Knotting, M/M, Mating Cycles/In Heat, Mpreg, Omega Sherlock, Past Mary Morstan/John Watson, Pregnancy
Language: English
Status: In-Progress
Published: 2014-12-16
Updated: 2014-12-16
Packaged: 2018-03-01 17:29:53
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,417
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2781668
Author URL: https://archiveofourown.org/users/CornishKid/pseuds/CornishKid
Summary: <blockquote class="userstuff">
              <p>Sherlock and John lived together for years as an Alpha and Omega flatmate without ever mating with one another, much to the astonishment of their peers. After Mary gives birth, however, John is met with a startling discovery. Sherlock helps him cope.</p>
            </blockquote>





	A Convenient Arrangement

**Author's Note:**

> This 100% full-throttle Omegaverse. Mpreg and all. If that's not your cup of tea, that's all right. If it is, proceed and comment :-)

Most people couldn't understand how they were able to do it -- an Alpha and Omega, living together as flatmates for several years without bonding or even sharing a heat together. The answer was quite simple, for those who were desperate to know: they never talked about it.

Ever.

Well, except once of course.

* * *

_John knows when he agrees to move in that Sherlock is an Omega. The consulting detective had been very upfront with that point from the start. For whatever reason, though, they'd neglected to discuss the matter. Somehow, it was forgotten a midst the serial suicide case and Bond nights. John figures Sherlock will pull him aside at some point and tell him that his heat is approaching. He's got Mike on speed-dial, just in case he needs to kip on someone's couch for a few days._

_No such conversation happens. Then John walks into the flat one afternoon to find the entire space saturated by the luscious smell of an unbonded Omega in heat. He is instantly hard in his trousers, overwhelmed with the desire to find the Omega in question and_ breed _\-- he didn't even comprehend that beneath the odor is a scent that he recognizes._

_He follows his nose down the hallway to Sherlock's room (perhaps that should be the next clue) and finds the door locked. So he does the thing any sensible Alpha preparing for a rut would do -- he breaks the door down._

_In the center of a tangle of sheets on Sherlock's bed lies the detective himself. Sherlock freezes at the sound of John crashing through the door. He has one hand on his prick, which is dark red and visibly weeping at the tip, and the other between his legs, holding a massive purple dildo with a faux knot attached at the bottom._

_There's a beat that lasts all of two seconds before many things happen at once. John, whose eyes have gone wide as he'd taken in the sight of his flatmate writhing on the bed, moves forward. Sherlock, who has already moved away, wrenches the dildo from his dripping arse, and flings it directly at the good doctor's head._

_"GET OUT!" Sherlock roars._

_The dildo strikes John between the eyes -- he stumbles back out into the hallway, which gives Sherlock enough time to leap from his bed and slam the door shut. John stands in the hallway with his head and cock throbbing in time with one another._

_"Sherlock --" he calls, but he's met with the sound of something scraping against the hardwood floor. Sherlock has shoved his bedside table in front of the door in a clear attempt to keep John from repeating his previous endeavor._

_John may be an Alpha, but he prides himself on being able to rise above his base instinct when the need arises. So he turns from Sherlock's door, picks the slicked dildo from the floor, and ascends the stairs to begin the most humiliating four-day wank of his life, using the leftover lubrication from the artificial dick to slick up his own cock._

_When both parties emerge from their heat-enduced haze, Sherlock hands John a calendar with his estrus cycles marked on it, and the silent agreement between the two of them to never discuss the matter begins._

* * *

 

Much happens after that initial encounter. They meet a mad Alpha with an affinity for Semtex, Sherlock fakes his death and then returns two years after, John gets married to a lovely Beta woman who turns out to be an assassin (causing John to rethink his initial assessment of 'lovely')... He stands by Mary for the sake of their child, and for a time John thinks his life may become something normal.

Until his daughter, a beautiful little Alpha girl, is born smelling of a completely different Alpha male. John detects it as soon as the wriggling baby is pulled from Mary and placed in her mother's arms.

Mary doesn't notice, of course. She's a Beta, and can't detect scent in the same way as Alphas or Omegas. Neither can most of the hospital staff, but John sees two of the Omega nurses raise their eyebrows and knows his humiliation won't be kept secret for long.

He waits in complete silence while the baby is cleaned and returned to Mary, steadfastly not looking at either of them. Mary is too absorbed in the newborn to notice John's silence. Perhaps she mistakes it for shock. That certainly seems like an emotion that could be playing across his face right now.

It's not until the doctors and nurses have left that Mary pays any attention to John.

"She's beautiful," Mary coos. "What should we call her? We never really discussed names --"

"Call her whatever you like," says John icily. "I expect her father will want a say. Best ask him."

Mary is very obviously confused. The baby starts to squirm discontentedly in her arms, sensing its' mother's agitation. John feels sick just being in the same room as the two of them.

"John," says Mary lowly, "what're you --?"

"Don't pretend you don't know!" John roars, jumping from his chair to loom over Mary. The baby gives a startled cry, which quickly evolves to full-fledged wailing. "She's not mine! She never was, only now I can smell it --"

Mary's eyes widen as the realization dawns on her. Now that she's aware of it, she can probably pick up on the fact that John's scent does not match the baby's.

"Oh my god," she whispers, looking from the shrieking infant that she's holding to John, whose jaw is clenching and unclenching as he grinds his teeth in fury. "Oh my god," she whispers again.

John isn't sure he wants to know, but he asks anyway.

"Who?"

"There's a pause in which Mary is obviously trying to decide whether to tell the truth. The baby's cries soften to whimpers as Mary absently rocks her back and forth.

"David," she says finally.

John nods once. It makes sense, he thinks as he glances at the baby. David and he look similar enough that Mary could have passed the baby off as his. He would never have known, if it weren't for the super-Alpha scent detectors in his brain.

"So you fucked David behind my back, found out you were pregnant, and then took the chance that it would be mine?"

"I didn't think there was any way she  _could_ be his," says Mary. "I was on birth control, and he and I used condoms --"

John silences her by raising a hand.

"I don't want the details, thanks," he says.

Mary swallows.

"What happens now," she asks.

John scoffs.

"What do you think?" he spits.

"That's it then?" she says, and there are tears forming in her eyes now. "You're done, just like that?"

"We've been done for a while now," John replies. It doesn't come out as an accusation; there's no malice in his voice. It's just a weary, simple statement of fact.

Mary smiles mirthlessly.

"That's true," she admits.

"Ever since you shot Sherlock --"

"Oh, who are we kidding, John?" says Mary. "Let's go all the way back -- this all fell apart the moment Sherlock came back from the dead."

John opens his mouth to deny it, and finds he can't. At his silence, Mary hugs her daughter closer to her chest.

"You should go," she says.

The way she says it -- the tone of her voice -- somehow implies that John is the one to blame for this whole scenario. That it's  _his_ fault for witnessing the birth of another man's child. He wants to shout at Mary, but finds he's tired of dealing with her. 

So he goes.

* * *

 

Sherlock frowns at his phone. It's been several hours since John's last text, and he hasn't received any updated news. Mary went into labor approximately eleven hours ago -- the baby should be here by now...

Perhaps he's judging by Omega birth standards. He really should have looked into Beta gestation and labor more. Foolish.

He's about to call and ask for an update directly when his phone rings. He answers before the first tone has faded away.

"Hello?" he says.

"Sherlock."

It's John, but something's wrong. He doesn't sound like the joyous new father that Sherlock had expected. He sounds exhausted (understandable) and forlorn (confusing).

"What's wrong?" says Sherlock at once.

"Can I come over?" is John's reply.

"Of course," Sherlock says. "The door is always open."

"Thanks," says John. "Is my old room still free?"


End file.
